Sporophyte. A spore-producing organism, especially in organisms in which the spore generation and the gamete generation alternate. In organisms in which the two generations alternate regularly, the sporophyte itself arises from the union of gametes, not from spores. The sporophyte and the gamete-producing gamete may appear to be the same shape and size, or they may differ in shape and size. In mosses, the gametophyte is the main life form, while in ferns, the sporophyte is the main life form. In seed plants and the so-called higher animals, the organism corresponds to the sporophyte in phylogenetic terms, and the gametophyte has degenerated into a portion of the cells and tissues directly involved in reproduction. Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information |
造胞体。胞子をつくりだす生物体の意であって,特に,胞子世代と配偶世代が交代して現れる生物について,胞子をつくる世代 (造胞世代) を区別していうときに用いることの多い語である。規則的に両世代が交代する生物にあっては,胞子体自体は配偶子の合体によって生じるのであり,胞子から生じるのではない。胞子体と,配偶子をつくりだす配偶体は,外見上は同形同大のこともあり,形と大きさが異なることもある。コケ植物では配偶体のほうがおもな生活形態であるが,シダ植物では胞子体のほうが主体である。種子植物およびいわゆる高等動物においては,その生物体は系統発生からみて胞子体に相当しており,配偶体はその内部で直接に生殖にたずさわる一部の細胞および組織へと退化している。
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